Double denim: How old jeans might gain a new life as artificial bone cartilage
Scientists at Australia's Deakin University have come up with a potential new way to reclaim some of the tremendous waste generated by the fashion industry. The team has developed a method that reduces discarded denim to the building blocks for artificial cartilage, something that, with further development, could become an advanced tool for performing joint reconstructions in humans.
The work was led by Dr Noelene Byrne, a scientist at Deakin's School of Engineering, and involves first applying a liquid solvent to dissolve the denim. Byrne tells us this solvent was developed in-house and she won't share its components right now for intellectual property purposes, but it has the effect of reducing the denim to cellulose.
"Cellulose is a versatile renewable material, so we can use liquid solvents on waste denim to allow it to be dissolved and regenerated into an aerogel, or a variety of different forms," she says. "Aerogels are a class of advanced materials with very low density, sometimes referred to as 'frozen smoke' or 'solid smoke,' and because of this low density they make excellent materials for bioscaffolding, absorption or filtration."
Aerogels formed from cellulose are nothing new, but nobody had ever tried making it with a cellulose sourced from denim before. The team found that in doing so, it produced an aerogel with a unique porous structure, featuring vertical nanoscopic tunnels throughout. The team believes the sticky nature of the denim-based cellulose is why these tunnels form, but whatever the reason, the material they are left with is perfectly formed for use as artificial cartilage.
"That's exactly what cartilage looks like – you can't 3D print that material – and now we can shape and tune the aerogel to manipulate the size and distribution of the tunnels to make the ideal shape," says Byrne.
The team is now working with scientists in the university's materials department to develop the aerogel further for these purposes. Byrne says the preliminary data suggests the denim-based aerogels out-perform regular cellulose aerogels. Other potential applications include membranes used in water filtration systems and batteries, though artificial cartilage is a primary focus.
"The remarkable similarity in the pore network structure of these aerogels and cartilage tissues – even down to the dimensions, orientations, and density distribution of pore channels – enables these materials to replicate a special type of 'weeping' lubrication mechanism used by cartilage to protect against wear and damage," said Dr Wren Greene, from Deakin's Institute for Frontier Materials.
Though the amount of denim this approach could save from landfill is likely to be minimal, at least at first, the team says its method could form a blueprint for smarter recycling methods that prove more cost-effective than existing approaches.
"One of the main drawbacks of textile recycling efforts is that any advanced technique requires the use of chemicals, which can then make the procedure less cost-effective," says Byrne. "We use environmentally-friendly chemicals, and by upcycling our approach to create a more advanced material we can address the limitations affecting other less cost-effective methods. We are now entering pilot-scale trials and look to be at commercial scale within three to five years with industry support."
Source: Deakin University